Barcodes are ubiquitous machine-readable representations of information. As is well known, barcodes usually comprise dark images printed on a light background to create high and low reflectance, which may be converted to digital data by a compatible scanner. Linear barcodes store data in the widths of and spacings between parallel lines.
Barcodes are read by optical scanners called barcode readers. Typically, a barcode reader includes a light source, a beam moving device such as a rotating mirror to cause the light beam to repeatedly sweep along a linear path, and an optical sensor that translates optical impulses into electrical ones. Additionally, most barcode readers include decoder circuitry configured to analyze the barcode's image data provided by the photo detector and sending the barcode's content to the scanner's output port.
One example of a type of reader is a pen or wand reader, which includes a light source and a photodiode that are placed next to each other in the tip of a pen or wand. To read a barcode, the tip of the pen moves across the lines in a steady motion. The photodiode measures the intensity of the light reflected back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the bar code. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is a representation of the bar and space pattern in the bar code. A decoder recognizes the barcode symbology, analyzes the content of the barcode scanned, and communicates corresponding data in a usable format to another device such as a computer. While pen readers are popular because they are inexpensive and reliable, in general they are not effective for scanning barcodes any appreciable distance from the tip because the light source is typically only focused enough to distinguish between bars and stripes at the tip.
Laser scanners work the same way as pen type readers except that they typically employ either a reciprocating mirror or a rotating prism to scan a laser beam back and forth across a bar code. The laser is usually a relatively inexpensive solid state laser that produces a red light, which is easy to detect. As with a pen type reader, a photodiode is used to measure the intensity of the light reflected back from the bar code. In both pen readers and laser scanners, the time rate of change, or rise and fall time, of the signal generated by the photo detector upon sensing reflected light is a principal means for distinguishing a bar signal from other sources of ambient light. Advantageously, today laser scanners are commonplace, relatively inexpensive and highly reliable, even when a barcode is askew and/or placed quite a distance away.
A shortcoming of conventional barcode systems is that the barcodes are static and not efficient for representing codes that may change over time. Typically, they are defined and imprinted directly on items or on packaging or labels attached to items that will be tracked. Applying the barcode is inexpensive and easy to do. Once applied to an item, a barcode does not change, unless it is physically removed and replaced by or covered with an alternative barcode. Thus, a conventional printed barcode may be used to identify an item, which may then be associated with information (e.g., price, quantity, relevant dates, origins, etc . . . ) in a database that pertains to the item. As barcode readers are commonplace and inexpensive, the barcoding system provides a convenient method for item identification. However, a conventional printed or embossed barcode is not useful for directly conveying variable information.
Another shortcoming of conventional printed barcodes is that they are readily visible, decipherable and reproducible. Thus, conventional printed barcodes are not well suited for applications that require confidentiality and security of the communicated code.
Yet another shortcoming of conventional barcodes is that their integrity is easily compromised. An accurate scan requires a clear presentation of the barcode stripes and spaces. Unfortunately, however, printed barcodes are easily mutilated and obscured by abrasion and soiling.
Still another shortcoming of conventional printed barcodes is that they are vulnerable to fraud. Conventional barcode labels are easily concealed and replaced. Unscrupulous consumers have been known to replace a correct UPC label with one for a less expensive product.
Many items and circumstances could benefit from the ability to securely and wirelessly communicate variable or static information in a manner readable by a conventional laser barcode scanner. By way of example and not limitation, such technology may be applied to security badges, fault code communication systems, and item identifiers, just to name a few. However, to compete effectively with alternative forms of wired and wireless information communication (e.g., RFID, IrDA, OBD), the device must be compact, reliable, adaptable and inexpensive. Costly, complex, bulky, unreliable and/or fragile solutions would not gain industry acceptance.
What is needed is a compact, reliable, adaptable, fraud-proof and cost effective alternative to conventional printed barcodes. Preferably, the alternative system is capable of detecting the presence of a conventional laser barcode scanner and communicating information in a form readable by the detected conventional laser barcode scanner. The invention is directed to overcoming one or more of the problems and solving one or more of the needs as set forth above.